Conduit grinding apparatus
The Government has rights in this invention pursuant to Contract No. DE-AC12-76N00052 awarded by the U.S. Department of Energy. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a grinding apparatus and, more particularly, to an apparatus for grinding weld defects in a valve stem receiving area of a valve. 
     2. Prior Art 
     Devices for grinding, machining and resurfacing cylindrical objects are well known in the art. U.S. Pat. No. 4,246,728 to Leasher discloses a tool for treating an end of a tubular conduit having a rotatable body. U.S. Pat. No. 4,362,447 to Pekar et al discloses an adjustable face milling cutter carried on a turntable rotatable about a central axis to machine a circular path on an upper tubesheet surface. U.S. Pat. No. 4,388,782 to Rodgers et al discloses a grinder for preparing circular seats behind elliptical handholes of marine boilers. U.S. Pat. No. 4,513,542 by Wilger et al discloses a portable surfacing machine for boiler manholes. U.S. Pat. No. 4,534,135 to Wilger et al discloses a grinding machine for watertight hatch lugs. And U.S. Pat. No. 2,772,529 to Dutro discloses a cylinder block ridge grinder. In addition, U.S. Pat. No. 4,696,544 to Costella discloses a fiberscopic device for inspecting internal sections of construction. 
     In the manufacture of large valves, such as steam stop valves, parts must be welded together. When welding is involved, such as welding a ring type insert onto the internal flow surface of a steam stop valve, defects can appear. In order to provide a functional valve, these welding defects must be removed. 
     It is therefore an objective of the present invention to provide a grinding apparatus that can be placed into a valve through the valve stem area when the valve actuator, bonnet and valve gate are removed. 
     It is another objective of the present invention to provide a grinder that can grind the interior of conduits having a pneumatic motor for grinding and a fiberscopic device for visual observations of the grinding operation. 
     It is another objective of the present invention to provide an interior conduit grinder that can remove a local defect while the device is clamped in place or remove a continual defect on the 360 degree inner circumference of the weld between a ring type insert and a valve body when the grinder is not clamped in place. 
     It is another objective of the present invention to provide a grinder with a grinder motor that is adjustable for various depths of cuts. 
     SUMMARY OF THE INVENTION 
     The foregoing problems are overcome and other advantages are provided by a grinding apparatus for grinding the interior of a conduit. 
     In accordance with one embodiment of the invention the grinding apparatus comprises a faceplate means, cam means, locking means and grinding means. The faceplate means is provided for positioning on a conduit aperture. The cam means is located on the faceplate means for rotatably mounting the faceplate means with a conduit aperture. The locking means is provided for locking the faceplate means in a predetermined position at a conduit aperture. The grinding means is movably mounted on the faceplate means whereby the grinding means can be fixed to the faceplate means at a predetermined position and the faceplate means can be rotated about a conduit aperture to axially rotate the grinding means to grind the inner circumference of a conduit, and the faceplate means can be locked at a predetermined position at a conduit aperture and the grinding means radially moved relative to the faceplate means to grind a specific interior portion. 
     In accordance with another embodiment of the invention, a weld grinding apparatus is provided for grinding welds in an interior portion of a valve stem receiving area of a valve. 
     The apparatus comprises faceplate means, means for mounting the faceplate means to a valve stem receiving aperture, grinding means and guide tube means. The faceplate means can be mounted over a valve stem receiving aperture. The means for mounting the faceplate means to a valve stem receiving aperture include cam means mounted on the faceplate means for contacting an interior portion of a valve stem receiving area, the cam means allowing the faceplate means to rotatably move about a valve stem receiving aperture. Locking means are provided for locking the faceplate means at a predetermined position. The grinding means is movably mounted on the faceplate means and comprises a motor means, a grinding wheel and a pivoting motor mount for movably mounting the motor means and grinding wheel relative to the faceplate means for substantially radial movement relative thereto. The guide tube means provides a passage for an instrument for viewing a target area therethrough. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and other features of the invention are explained in the following description, taken in connection with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a first side of a weld grinding apparatus incorporating features of the present invention. 
     FIG. 2 is a perspective view of the opposite side of the weld grinding apparatus shown in FIG. 1 attached to a valve stem receiving area of a valve. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to FIG. 1, there is shown a perspective view of a grinding apparatus 2 incorporating features of the present invention. The grinding apparatus 2, in the embodiment shown, is a weld grinding apparatus for use in grinding welds in an interior portion of a valve at a valve stem receiving area. However, the present invention can be used for grinding or performing other operations in the interior of any conduit having an aperture. The grinding apparatus 2 generally comprises a faceplate 4, three cam assemblies 6, 8 and 10, a locking bolt assembly 12, a guide tube assembly 13 and a grinder assembly 14. The faceplate 4, in the embodiment shown, has a disc like shape with various apertures passing therethrough. The faceplate 4 may be made from any suitable material such as metal. In the embodiment shown, the faceplate 4 also comprises a handle 16 for an operator to rotatably manipulate the grinding apparatus 2 as will be described below. In the embodiment shown, the faceplate 4 comprises a grinder assembly aperture 18, a locking bolt assembly access aperture 20, a guide tube aperture 22 (see FIG. 2) two cam assembly apertures (not shown) for passage of a portion of the first and second cam assemblies 6 and 8 therethrough and a third cam assembly aperture 24 for passage of the third cam assembly 10 therethrough. 
     The grinder assembly 14 generally comprises a movable motor mount 26, an adjustable shaft 28 and a grinding wheel 30 (see FIG. 2). The movable motor mount 26, in the embodiment shown, is pivotably mounted to the faceplate 4 at a first end 32 and adjustably mounted to the faceplate 4 at a second end 34 via a slot 36 and bolt 38. The shaft 28 is adjustably mounted to the motor mount 26 for longitudinal movement therein. The set screw 40 can fix the longitudinal location of the shaft 28 relative to the motor mount 26 at a desired location. A first end 42 of the shaft 28 is suitably sized and shaped for connection to a pneumatic motor to provide axial rotation for the shaft 28. The shaft 28 has a second end 44 located at the opposite side of the faceplate (see FIG. 2) with the shaft 28 passing through the grinder assembly aperture 18. 
     The guide tube assembly 13 generally comprises a guide tube 46 (see FIG. 2) and a guide tube mount 48 (see FIG. 1). The guide tube 46 is fixedly mounted to the guide tube mount 48 with a portion thereof passing through the guide tube aperture 22 in the faceplate 4. The guide tube mount 48 generally fixedly connects the guide tube 46 with the faceplate 4. The guide tube 46 is generally provided for providing a path for an instrument, such as a fiber optic scope (not shown), for viewing a desired target area. As shown in FIG. 2, the guide tube 46 extends through the faceplate 4 and is bent in the direction of the grinding wheel 30. Thus, an instrument such as a fiber optic scope (not shown) can be passed through the guide tube 46 from the first side of the faceplate 4 shown in FIG. 1 to the second side of the faceplate shown in FIG. 2. In a preferred embodiment the guide tube 46 is stationary relative to the faceplate 4. However, in an alternate embodiment, the guide tube 46 may be movable relative to the faceplate 4. 
     Referring also to FIG. 2, the cam assemblies 6, 8 and 10 shown in FIG. 1 each generally comprise a shaft 50, a nut 52 and a rotatable cam 54 (FIG. 2) rotatably mounted to the shaft 50. In the embodiment shown, the first and second cam assemblies 6 and 8 are stationarily mounted to the face plate 4 with only the cams 54 being movable. The third cam assembly 10 is adjustably mounted in the elongate cam assembly aperture 24 and can be adjusted and fixed at different locations in the aperture 24 as desired. The cams 54 are suitably mounted on the faceplate 4 for contacting the interior portion of an aperture for rotatably mounting the grinding apparatus 2 at the aperture as indicated by arrow A. In the embodiment shown in FIG. 2, the grinding apparatus is shown rotatably mounted at an aperture to a valve 56 at a valve stem area where the valve actuator, bonnet and valve gate have been removed. 
     The locking bolt assembly 12 generally comprises a bolt 58 and a housing 60. The housing 60 is fixedly connected to the faceplate 4 on the interior side of the faceplate with the bolt 58 threadingly engaged with the housing 60 for movement as indicated by arrow B. The locking bolt assembly access aperture 20 allows an operator to have access to the bolt 58 when the grinding apparatus 2 is attached to a valve. The bolt 58 is generally intended for contacting an interior portion of the valve 56 and act as a locking device to lock the grinding apparatus 2 at a predetermined position at the valve 56. When the bolt 58 clampingly engages the valve 56 the grinding apparatus 2 is prevented from axial rotation and is locked in place. With the bolt 58 not in contact with the valve 56, as shown in FIG. 2, the grinding apparatus 2 is substantially fee to rotate as indicated by arrow A. 
     The grinding apparatus 2, in the embodiment described above, is generally capable of grinding an internal surface area of a conduit or valve. The cam assemblies 6, 8 and 10 allow the grinding wheel 30 to remove or grind a specific area on a 360° circumference as the grinding apparatus 2 is rotated about its axis. An operator can rotate the apparatus with the aid of the handle 16. The adjustable motor mount 26 allows the grinding wheel 30 to be moved radially relative to the faceplate. This allows the grinding wheel 30 to contact the interior of the conduit for various different depths of grinds or cuts. In addition, with the use of the locking bolt assembly 12, the grinding apparatus 2 may be locked at a specific location at a conduit or valve for concentrated grinding at a specific interior portion to remove a local defect. Thus, the grinding apparatus 2 can remove both a local defect as well as a continual defect on a 360° circumference. In addition, the guide tube assembly 13 allows insertion of a fiber optic scope behind the faceplate 4 for observation of the setting up of the grinding equipment and observation during the actual grinding operation. 
     It should be understood that the foregoing description is only illustrative of the invention. Various alternatives and modifications can be devised by those skilled in the art without departing from the spirit of the invention. Accordingly, the present invention is intended to embrace all such alternatives, modifications and variances which fall within the scope of the appended claims.